How to Calculate What a Bridging Loan Will Actually Cost

Type an amount, a term and a rate into a bridging loan calculator and it hands back a tidy monthly figure. That figure is almost always smaller than the real cost of the loan, and the reason is structural rather than dishonest. A calculator models the one input everybody understands, the monthly rate, and quietly ignores the two that decide the outcome: how the interest on the loan is charged, and what comes out of the advance before you ever see it.

Borrowers get caught by this at the worst possible moment. The deal is agreed, the solicitor is instructed, and the completion statement shows a net advance tens of thousands below the loan amount. Nobody moved the goalposts. The arithmetic behind bridging loans was always going to do that. It simply was not on screen.

What inputs does a bridge finance calculator need?

A bridging loan is short-term borrowing secured by a legal charge over property and repaid from a defined exit. Modelling one honestly takes more than three boxes on a form.

Six inputs move the answer, and most bridging loans are mispriced in a borrower’s head because two or three of them were never entered into the calculator at all.

The gross loan. The headline facility. This is the number the lender registers against the title and the number you repay at the end of the loan.

The monthly rate. Bridging finance is quoted per month, not per year. Across our lender panel bridging loans run from 0.55 percent to 1.0 percent a month, and where a loan sits in that band is set by leverage, security and exit strength rather than by negotiation.

The term. Bridging loans run 1 to 18 months. Interest is charged by the month, so the term is a direct multiplier on the cost of the loan and the single largest lever a borrower controls.

The interest method. Retained, rolled up or serviced. This changes what leaves your account each month and what you receive on day one, and no simple loan calculator asks about it.

The arrangement fee. Typically 1 to 2 percent of the gross loan across our lender panel, deducted from the advance rather than invoiced later.

The third party costs. Valuation, your legal fees, the lender’s legal fees, and sometimes an exit fee. Small individually. Material as a block, and these costs are precisely what a public bridging loan calculator strips out to keep the interface simple.

Enter only amount, rate and term and you have modelled roughly two thirds of the bridging finance you are about to take on.

How do you calculate a bridging loan amount?

Start from the security rather than from what you want to borrow. Bridging lenders size a loan against value, and the ceiling is a straight multiplication.

We arrange bridging loans up to 75 percent loan to value on residential security and 65 to 70 percent on commercial. So a residential asset valued at £600,000 supports a maximum gross loan of £450,000, and a commercial unit at the same value supports £390,000 to £420,000. That is how much you can borrow before anything else is considered.

Two adjustments then bite, and neither of them appears in a calculator.

The valuation the lender uses is its own surveyor’s figure, not the purchase price and not the agent’s appraisal. Where the surveyor comes in below expectation, the loan shrinks by 75 pence in the pound on residential security. Borrowers plan around an optimistic value more often than they plan around anything else, and bridging lenders discount optimism as a matter of routine.

Where there is an existing charge, the calculation runs on the equity behind it. A property worth £600,000 with £250,000 outstanding to a first lender leaves £200,000 of headroom at 75 percent, not £450,000. Second charge bridging loans are priced higher for exactly that reason, and fewer lenders write them.

For a refurbishment case the arithmetic splits again. There is a day one advance against current value, then a works facility drawn in stages against a schedule the lender has approved. The day one figure is what a bridging loan calculator shows you. The works tranche is what actually pays the builder, and leaving it out of the model is how a scheme runs out of money in month four.

Gross or net: which figure is the calculator showing you?

This is the distinction that catches people, and it is worth slowing down for.

The gross loan is the total facility. The net advance is the cash that reaches your account. On most bridging loans they are not the same number, because the lender deducts the retained interest and the arrangement fee from the gross before releasing funds.

Work a real facility through. Take a £450,000 gross bridging loan over 9 months at 0.75 percent a month, interest retained.

Retained interest is 9 months at 0.75 percent of £450,000, roughly £30,400 once the lender’s own gross-up method is applied. The arrangement fee at 1.5 percent is £6,750. Deduct both and the net advance is about £412,850. You still repay £450,000 at redemption.

So the client account sees roughly 92 percent of the loan. If you needed £450,000 in cash to complete the purchase, you are £37,000 short and you found out three days before completion.

Run it the other way and the problem disappears. Decide the cash you need, then gross up. To receive £450,000 net on the same terms, the gross loan has to be roughly £490,000, which needs a property worth about £654,000 at 75 percent loan to value. That is the calculation a broker does first and an online calculator never does at all.

Ask any lender, in writing, whether a quoted number is the gross loan or the net advance. It is the single most useful question in the whole of bridging finance.

How is bridging loan interest calculated month by month?

Interest on bridging loans is charged monthly on the outstanding balance. Whether that balance moves depends on the method, and the method changes the total cost of the loan.

Serviced. You pay the interest each month from your own cash flow. The loan balance stays flat. On £450,000 at 0.75 percent that is £3,375 a month, £30,375 over 9 months, with no compounding at all. This is the cheapest of the three and it needs income from day one.

Retained. The lender calculates the full term’s interest at the outset and holds it back from the loan. Nothing is paid monthly. You receive less cash. Redeem early and unused retained interest is normally refunded, though you should confirm the rebate terms in the offer rather than assuming them.

Rolled up. Nothing is deducted and nothing is paid. Interest accrues onto the balance, and next month’s interest is charged on the larger figure. This is where a simple calculator diverges from reality. A £450,000 loan rolled at 0.75 percent for 9 months reaches roughly £481,300, so the interest is about £31,300 rather than the £30,375 a straight multiplication suggests. Over 9 months the compounding costs under £1,000. Over 18 months at 1.0 percent it costs considerably more, and a linear bridging loan calculator understates it every time.

Two further mechanics change the number and appear in no online tool. Some lenders charge interest on the gross loan including the retained interest and the fee, which is dearer than charging on the net advance. And most lenders apply a minimum term, commonly 1 to 3 months, so redeeming a loan in week 3 does not mean paying 3 weeks of interest.

How much is a 200k bridging loan?

The question gets asked constantly, and the honest answer opens with a second question: over how long, and charged how? Without those two inputs the number is guesswork.

Take £200,000 gross, 6 months, retained interest, 0.65 percent a month, first charge on a residential investment property.

Interest is 6 months at 0.65 percent, about £7,800. The arrangement fee at 1.5 percent is £3,000. Valuation on a straightforward residential asset commonly runs £500 to £1,200. Legal costs for both sides commonly run £1,500 to £2,500. Total cost of the loan is therefore roughly £13,000 to £14,500 for 6 months, and the net advance is around £188,000 rather than £200,000.

Change one input and watch what happens. Hold the same £200,000 loan for 12 months instead of 6 and the interest doubles to about £15,600 while every other line stays flat. Take it at 1.0 percent instead of 0.65 percent, because the security is unusual or the exit is open, and 12 months of interest reaches £24,000.

That spread, roughly £13,000 at the cheap short end against roughly £29,000 at the dear long end on the same £200,000 loan, is the entire argument for modelling bridging loans properly. The rate moved by less than half a percent a month. The bill nearly doubled, and the term did most of the work.

It is also why asking how much a 200k bridge costs, with no other detail, cannot be answered by any calculator honestly. Every figure here is indicative and none of it is an offer of finance.

What fees does an online bridging calculator leave out?

Nearly all of them, and the fees are where two apparently identical bridging loans separate.

Arrangement fee. 1 to 2 percent of the gross loan across our lender panel. On £200,000 that is £2,000 to £4,000. Almost never shown in a public calculator.

Valuation fee. Payable to the lender’s own surveyor and payable whatever happens afterwards. It scales with property value and complexity. Lenders that instruct a valuation before properly reading a case can cost you this fee for nothing.

Legal fees, twice. Yours and the lender’s, and you pay both. On bridging loans the legal work is the most common source of delay, so lenders with a responsive panel firm are often worth more than a small saving elsewhere.

Exit fee. Charged by some bridging lenders and not others, typically 1 percent of the loan or one month of interest. A loan with no exit fee and a marginally higher monthly rate frequently beats the reverse over a short term.

Broker fee. Some brokers charge one, some are paid by the lender, some do both. Ask which, and ask for the figure in pounds, in writing, before any application is submitted. A broker who will not answer that question has told you something useful.

Administration charges. Redemption admin, telegraphic transfer fees, title insurance premiums, and a re-inspection fee on staged refurbishment drawdowns. Individually small. Worth reading as a block, because these costs land at the point you have no room to argue.

Default interest. The line nobody models and the one that hurts. If the loan runs past term the rate steps up, often to several times the headline monthly figure. Ask what it is and ask what triggers it.

Added to a 9 month facility, the fees commonly represent 2.5 to 4 percent of the loan on top of the interest. A calculator showing you interest alone has shown you perhaps three quarters of what the borrowing costs.

What does a larger bridging facility cost in practice?

Scale changes the shape of the answer, so work through something bigger than a house.

A developer buys a vacant office building at £1,100,000 with consent to convert to 9 flats. The valuation supports £1,100,000, the lender offers 65 percent on commercial security, so the gross loan is £715,000. The term is 15 months, the rate 0.85 percent a month, interest rolled up, because an empty building produces no income to service anything.

Rolled at 0.85 percent for 15 months, £715,000 becomes roughly £811,600, so the interest is about £96,600. The arrangement fee at 1.5 percent is £10,725. Valuation on a commercial building of that size is materially dearer than on a house, commonly £2,500 to £5,000. Legals for both sides on a conversion with planning conditions attached, call it £6,000 to £9,000.

Total costs of the loan over 15 months land near £116,000, about 16 percent of the facility. The net advance on day one, after the fee, is around £704,000, and the developer needs the balance of the purchase price and every penny of the works from elsewhere.

Whether £116,000 is expensive depends entirely on what it bought. If the alternative was losing a consented building, it is cheap. If the conversion could have run on staged development finance at a lower rate, it is not, and that is a conversation worth having before the bridging loan is drawn rather than after it is.

Is a bridging loan a good idea to buy a house?

For a residential purchase the answer turns on which house and whose name is on the deeds.

Buying an investment property, a rental, a flip, or a house nobody will mortgage until it has a working kitchen, bridging finance is often the only route that exists. Mortgage lenders decline uninhabitable stock as a matter of policy, and no amount of deposit changes that. A bridge buys the property, the works make it mortgageable, and a mortgage repays the loan. That sequence is the standard refurbishment play and it is what bridging loans were built for.

Buying a home for yourself or a close family member, the picture changes. That is a regulated mortgage contract, and Construction Capital is not authorised by the FCA, so where a case is a regulated activity we arrange it through lenders who hold the relevant FCA permissions. Chain break bridging on a main residence can be entirely sensible when a sale has exchanged and a purchase has to complete first. It is far less sensible when the sale has not exchanged, because then you are borrowing against a hope at a monthly rate.

The test is not whether the loan is expensive. It is whether the thing that repays it is a document or an intention.

Why a consumer loan calculator misleads on development deals

Consumer money advice treats short-term secured borrowing with caution, and the caution is well aimed. A household using a bridge to cover a personal shortfall, against the roof over its head, at a monthly rate with fees on top, is taking a genuine risk. Anyone in that position should take regulated advice before anything else.

The tools built for that audience carry the same assumptions. A consumer loan calculator assumes a single repayment stream, no retained interest, no gross-up, no staged drawdown and no exit fee. Feed a conversion scheme into it and every one of those assumptions is wrong.

Development and investment bridging is a different activity. It is working capital with a modelled exit and a defined job, compared against the cost of the deal not happening rather than against a mortgage rate. Both things stay true at once: bridging loans are high cost money, and for the right job they are the right money.

The general purpose calculator on a comparison site is not lying to you. It is answering a different question, for a different borrower, with a different mortgage-shaped product in mind.

Which bridging lenders will a calculator never tell you about?

Search bridging loan how much can I borrow and you get a loan to value figure back. That figure is the ceiling across the market as a whole. It is not what any particular lender will actually advance on your particular deal, and the difference between those two things is most of the work.

Bridging lenders are not one market. Clearing banks, challenger banks, principal lenders funding from their own balance sheets, debt funds and private capital all write bridging loans, and each camp has a different appetite, a different cost of money and a different idea of acceptable security. Our lender panel spans over 100 of them precisely because no single lender covers the range.

A calculator cannot model that, because appetite is not a number. Some bridging lenders will not touch a part-built scheme at any leverage. Some will lend on it at 65 percent and price it at the top of the 0.55 percent to 1.0 percent a month band across our lender panel. Some will do 70 percent but want a personal guarantee and a monitoring surveyor. Feed the same inputs into a single tool and you get one answer, when the honest answer is a range of live positions that shift with each lender’s funding line every quarter.

That is also why a rate found on a lender’s own bridging loan calculator is a starting position rather than an offer. It reflects that lender’s best case, on its cleanest security, for its preferred borrower. Bridging lenders publish the number that gets the phone to ring, and the credit committee prices the deal afterwards.

The practical consequence for a borrower is simple. Model the cost yourself so you can read a quote, then let a broker run the actual market once rather than approaching six lenders separately and collecting six credit searches against your file. The modelling tells you whether a deal works. The lenders tell you whether it funds.

What should you ask before you accept a bridging quote?

A bridging quote becomes comparable once you have eight answers, and any broker or lender worth using will give them without being chased.

Is the figure quoted gross or net, and what is the net advance on day one? Is the interest retained, rolled up or serviced? Is interest charged on the gross loan or on the net advance? What is the minimum term? Is unused retained interest refunded on early redemption? What are the arrangement, exit and broker fees in pounds rather than percentages? What is the default rate if the loan runs past term? And what exactly do the lenders need to see before they will fund?

Then compare bridging loans on total cost to a realistic redemption date, every fee included, and add two months to your own timetable before you run the numbers. Borrowers consistently underestimate how long works and sales take, and on a monthly product that optimism is expensive. A quote that assumes 9 months and delivers 12 has understated the interest by a third.

The Bank of England base rate of 3.75 percent, held since December 2025, sits under all of it as the floor on the cost of money, though bridging loan rates track each lender’s own funding lines rather than base rate directly. That is why the same case sent to different bridging lenders comes back at different numbers in the same week, and why running the market once through a broker beats guessing at a calculator.

If you want that arithmetic run against a live deal rather than a generic tool, we quote a bridging loan properly across a panel of over 100 lenders, gross and net, with the fees stated in pounds. Where the works are the main event rather than the purchase, refurbishment finance may model better. On a ground-up scheme, that is development finance, and the drawdown schedule replaces the calculator entirely.

Construction Capital is a trading name of Lenzie Consulting Ltd, registered in England and Wales, company number 08174104. We are a commercial finance broker and introducer, not a lender, and we are not authorised by the FCA. Rates, fees and terms are indicative, vary by lender and deal, and are never an offer of finance. Written by Matt Lenzie.